This invention relates to a keyboard musical instrument and, more particularly, to a keyboard musical instrument equipped with key actuators for selectively moving, the keys.
An array of solenoid-operated key actuators is assembled with an acoustic piano, and a controller selectively energizes the solenoid-operated key actuators for performing a tune without fingering on the keyboard. Thus, the array of solenoid-operated key actuators and the controller serve as an automatic player.
The solenoid-operated key actuators and the controller further behave as a tutor. The controller renders the solenoid-operated key actuators projecting the plungers immediately before times to generate the piano tones in order to notify the keys to be depressed to a trainee. Although the solenoid-operated key actuators fully project the plungers so as to give rise to free rotation of the hammers through escape of the jacks in the automatic playing, the controller is expected to control the solenoid-operated key actuators for stopping the plunger before the free rotation of the hammers in guiding the trainee. The keystroke between the rest position and the escaping point is short. If the keystroke is too short, the key motion may escape trainee""s attention. On the other hand, if the keystroke is too long, the hammer unintentionally starts the free rotation. Thus, the accurate key control is required for the electric tutor.
The prior art electric tutor controls the keystroke through adjustment of the time period to energize the solenoid-operated key actuators. The time period is experimentally determined for the solenoid-operated key actuator to be assembled with the acoustic piano. A problem is encountered in the prior art electric tutor in the large amount of time and labor consumed in the experiment. This is because of the fact that the keystroke is different between models of the acoustic piano. The manufacturer needs measuring the key-stroke for all the models of the acoustic piano, and takes the electromagnetic characteristics of the solenoid-operated key actuators to be assembled with each model of the acoustic piano into account. The manufacturer decides an appropriate time period for energizing the solenoid-operated key actuators. Thus, the experiment is time-consuming.
Another problem inherent in the prior art electric tutor is aged deterioration of the solenoid-operated key actuators. Even if constant electric power is applied to the solenoid-operated key actuator, the electromagnetic force is gradually decreased. This means that the solenoid-operated key actuators can not move the associated keys to the target positions by the initially adjusted electric power. Finally, the keys are scarcely moved, and the prior art electric tutor is rendered useless.
It is therefore an important object of the present invention to provide a keyboard musical instrument, key actuators of which are accurately controlled regardless the aged deterioration and the difference in model.
To accomplish the object, the present invention proposes to stop plungers when keys reach predetermined points on the way toward the rest positions.
In accordance with one aspect of the present invention, there is provided a keyboard musical instrument comprising a keyboard having plural keys movable between rest positions and end positions, plural mechanisms connected to the plural keys and selectively actuated by the keys moved from the rest positions to the end positions, plural key actuators having respective moving members associated with the plural keys and movable between retracted positions and projected positions for moving the plural keys from the rest positions to the end positions, plural key sensors associated with the plural keys for detecting transit of terminative points on the way between the rest positions and the end positions for producing detecting signals and a controller connected to the plural key actuators and the plural key sensors, selectively activating the plural key actuators so as to move the moving members from the retracted position toward the projected positions and responsive to the detecting signals for stopping the moving members at intermediate positions on the way to the projected positions.